This application claims priority from Japanese Patent Application No. 2002-052214, filed Feb. 27, 2002.
The present invention relates to an apparatus and method of assembly for a personal computer keyboard switch. More particularly, the present invention pertains to a keyboard switch that can be used in thin notebook type personal computers.
With the advent of desktop computers, the keyboard switch has been widely used as a data input device, and because of technological advances in computer technology such use has significantly increased over the years. Advances in technology are responsible for the significant miniaturization of notebook computers and other portable data devices that has taken place over the last few years. The height of some notebook computers is less than two centimeters. To accommodate the reduction in height of notebook computers, the structure of the keyboard switch has also necessarily evolved. Developments in keyboard switch technology include the use of a film-membrane structure that contains a plurality of keyboard switches. The keyboard switches are configured in the form of thin structures called pantographs and are positioned on the film-membrane.
An example of such a keyboard switch is disclosed and described in Japanese Laid Open Patent Publication No. Hei 6/1994-36647. Publication No. Hei 6/1994-36647 discloses a pantograph type keyboard switch structure that has a first intersecting member which is formed by allowing an extending section to extend in one direction. The extending section extends from the upper side of a rotation support section with it as the center and two link members each of which have arms that extends parallel to the extending section in the other direction from the lower side thereof so as to intersect each other at an intersecting point at the upper side from the center of the mutual arms in a rotatable manner. A second intersecting member having the same structure as the first intersecting member is arranged and placed a certain distance from the first intersecting member, thereby forming a pantograph shaped member, the tip section of the link member positioned at the one side with the intersecting point of the intersecting members as a center is allowed to be supported by a shaft on a holder plate arranged on a flexible circuit board and at the underside of a keytop in a freely rotatable manner, and at the same time the tip section of the link member positioned at the opposite side is allowed to be supported with respect to the holder plate and the underside of a keytop in a freely rotatable manner and in a freely slidable and movable manner, in such a manner that when the key top is pressed down, a switching member may be actuated by an attaching rod of the pantograph shaped member and at the same time the extending sections of the folded pantograph shaped member may be kept in parallel.
In conventional keyboard switches, such as the example given above, a rod attached to the pantograph shaped keyboard switch makes contact with an elastic tactile rubber cap when the keytop is pressed, thereby actuating the keyboard switch. This configuration may not allow the height of the pantograph structure to be reduced sufficiently to accommodate the reduced height requirements present in notebook computers. In addition, in conventional keyboard switches the keytop is directly attached to the upper ends of the pantograph keyboard switch structure, thereby making the pantograph structure and keytop inseparable. As a result, when removal and/or replacement of a keytop are desired, the pantograph structure must also be removed and replaced or disassembled.
In general the first aspect of the present invention features a keyboard switch that includes a pantograph structure. The pantograph structure has a first frame member and a second frame member. The first frame member has two cross arms fixed and parallel relative to each other and the second frame member has two cross arms fixed and parallel relative to each other. The first frame member and the second frame member engagedly intersect at an intersection point located below the center of the cross arms of each frame member forming an roughly X-like structure so as to allow free rotational movement of the first frame member and the second frame member about the intersection point to provide vertical movement for a keytop.
The keyboard switch also includes a coupling plate coupled to the underside of the keytop, a base plate, wherein the base plate is pivotally coupled to the lower ends of the cross arms of the first frame member by protrusions that extend from the cross arms so as to allow at least partial rotational movement. The base plate is also pivotally coupled to the lower ends the cross arms of said second frame member so as to allow at least partial sliding movement which may be in the direction roughly perpendicular to the direction of movement of the keytop. The upper ends of the first frame member and the second frame are moveably coupled to the coupling plate, wherein the coupling plate is also coupled to the underside of keytop so as to allow the keytop to be removed from or attached to the coupling plate. The switch further includes an elastic cap, wherein the elastic tactile cap is positioned between the coupling plate and the base plate.
An embodiment of the present invention may include the keyboard switch mentioned above, wherein the intersection point is one-third from the bottom of the cross arms of the first and second frame members.
Another embodiment of the present invention may include the keyboard switch mention above, wherein the first frame member has a first shaft receiving section that includes a shaft receiving groove and a shaft receiving plate having an arc section so that the shaft receiving plate is adjacent to the shaft receiving groove at the inner side of each cross arm. The second frame member may have a second receiving section that includes a shaft receiving groove and a shaft receiving plate having an arc section adjacent to each other at the outer side of each cross arm. The shaft receiving plate of second shaft receiving section engages into the shaft receiving groove of the first receiving shaft second and may allow free rotational movement and at the same time, the shaft receiving plate of first shaft receiving section engages into the shaft receiving groove of said second receiving shaft second an may also allow at least partial rotational movement.